"Back then, they didn't have the flat tops and all this, so they cook in a cast-iron skillet," Dyer's owner Tom Robertson says. "As you cook more burgers, the grease grows, and eventually it becomes a deep-fried hamburger. We strain and process our grease daily, but we've never thrown it out and started over, so somewhere in there's molecules from 1912. That's what makes it so good."